Decelopment of an array of pressure sensors and its application to turbulent flows = 다중배열 압력센서의 개발과 난류유동장에 대한 적용

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A new type of an array of pressure sensors, which is composed of PVDF (polyvinylidenefluoride), was devised and evaluated. In order to obtain the system transfer function of the PVDF system, a dynamic calibration was performed utilizing the signal from a 1/8 inch B&K microphone as input. The time history of the unsteady pressure was then reconstructed from the output of the sensor by using this transfer function. The reconstructed pressure signals showed good agreement with the reference signal in both a temporal and spectral sense. This sensor was then used to measure the wall pressure fluctuations in a two-dimensional turbulent channel flow. Various statistical moments were obtained from the measurement data set. Comparison of these quantities with the existing studies demonstrated satisfactory agreement. These exercises give credence to the relevance and reliability of this sensor for applications in more complicated turbulent flows. Laboratory measurements were made of wall pressure fluctuations in a separated and reattaching flow over a backward-facing step. An array of 32 microphones in the streamwise as well as the spanwise directions was utilized. The statistical properties of pressure fluctuations were scrutinized. Emphasis was placed on the flow inhomogeneity in the streamwise direction. One-point statistics such as the streamwise distribution of rms pressure and autospectra were shown to be generally consistent with the prior results. The peak frequency and the fall-off rate of autospectra demonstrated the shear layer-originated nature of pressure fluctuations. The coherences and wavenumber spectra in the streamwise and spanwise directions were indicative of the presence of dual modes in pressure; one is associated with the large-scale vortical structure in the low-frequency region and the other is the boundary-layer-like decaying mode in the high-frequency region. Time-dependent characteristics of wall pressure fluctuations in separated and reatta...
Advisors
Sung, Hyung-Jinresearcher성형진researcher
Description
한국과학기술원 : 기계공학전공,
Publisher
한국과학기술원
Issue Date
2000
Identifier
158011/325007 / 000945312
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 기계공학전공, 2000.2, [ xv, 124 p. ]

Keywords

Pressure fluctuations; Array of pressure sensors; Turbulent separated and reattaching flows; 난류 박리재부착 유동; 압력변동; 다중배열 압력센서

URI
http://hdl.handle.net/10203/42999
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=158011&flag=dissertation
Appears in Collection
ME-Theses_Ph.D.(박사논문)
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